Hannover - In recent months, KraussMaffei Berstorff has recorded an increased demand for extrusion lines for the production of photosensitive sheets for offset printing. In only one year, several lines for this application have been set up in Asia and North America. One of our Asian customers has already placed an order for the second line because of the extremely positive experience gained so far.

Sensitive processing“Photosensitive sheets made of styrene-isoprene-styrene block copolymer (SIS) with a thickness of 1 to 7 mm are produced for offset printing,” explains Marco Schönekäß, Sales Engineer for Film and Sheet Extrusion Lines at KraussMaffei Berstorff. “These sheets are covered with a printing film that is provided with a cut-out in the area of the pattern to be printed. Cross-linking of the material is then produced by ultraviolet light applied to the area in question. After the non-cross-linked material has been chemically washed in a final step, the printing sheet with the desired printing pattern is finished. This printing sheet can be used for wide variety of products,” adds Marco Schönekäß.

The production of these sophisticated sheets requires in-depth process and processing know-how. Throughout the entire production process up to cross-linking, the sheets are extremely susceptible to deformation. This is why they are covered with protective film on both sides after the extrusion process and must be handled with utmost care during processing. Homogeneous mixing of all components within the extruder, highly sensitive melt passage and controlled sheet cooling to the final temperature without any warping are additional challenges to be met. “The processing of low-viscosity, sticky and temperature-sensitive melts involves high demands on the entire extrusion line – in particular in view of the wide thickness range required in offset printing with a tolerance of +/- 1%,” declares Marco Schönekäß.

Extensive product range in the field of extrusion and polishing equipmentThanks to the extensive range of single-screw extruders and counter-rotating or co-rotating twin-screw extruders, KraussMaffei Berstorff is in a position to meet virtually all requirements. In-depth know-how in the field of customized polishing calenders should not be left unmentioned. The portfolio comprises horizontal, vertical and inclined versions, the J configuration up to the extremely flexible patent-registered planet calender, which all come with different number of polishing and cooling rolls and in various dimensions. Depending on customer requirements, KraussMaffei Berstorff develops and manufactures complete production lines – starting from material feeding up to the wound-up, stacked or packed final product.

Twin-screw extruder for inline compoundingAn Asian customer opted for a flexographic sheet extrusion line equipped with a co-rotating twin-screw extruder for in-line compounding of its proprietary recipes and gentle raw material processing. The line is designed for output rates of 350 kg/h when producing sheets of 5 mm thickness. This gives enhanced production flexibility and cost-effectiveness of the entire process. Due to the high degree of satisfaction, the customer has already ordered a second line.